A hernia can occur if there is a weakness in a part of the muscle layer that encloses and supports the abdominal organs, such as the bowel and stomach. A hernia can be identified as a lump that is felt under the skin at the site of the weakness in the muscle layer. Quite commonly the lump will appear when movement or straining causes the abdominal contents to be pushed through the area of weakness.
The most common site of a hernia is in the groin. The hernia will protrude through a natural small weakness in the abdominal wall, where in men the blood vessels supplying the testes travel from inside the body through the abdominal wall in the groin, and into the scrotum.
Other common sites for a hernia include around the umbilical region where there is a natural weakness of the tissues. These hernias are more common in women after pregnancy or in people who are overweight.
An incisional hernia can occur through the previous abdominal scar, again through a natural area of weakness of the abdominal wall.
A hiatus hernia is a weakness in the diaphragm which leads to a protrusion or herniation of the stomach from the abdomen through into the thorax. These hernias are commonly associated with heartburn type symptoms.